A case of adaptation through a mutation in a tandem duplication during experimental evolution in Escherichia coli

BMC Genomics

Research Article

Olivier Tenaillon¹  Joël Gaffé²  Jessica Plucain²  Dominique Schneider²  Martin Schliep³  Thomas Ferenci³  Ram P Maharjan³  Lei Wang⁴  Lu Feng⁴ 

[1] INSERM, UMR-S 722, F-75018, Paris, France;Université Paris Diderot, Sorbonne Paris Cité, UMR-S 722 INSERM, F-75018, Paris, France;Laboratoire Adaptation et Pathogénie des Micro-organismes, Université Joseph Fourier Grenoble, BP 170, F-38042, Grenoble cedex 9, France;CNRS UMR5163, F-38042, Grenoble cedex 9, France;School of Molecular Bioscience, University of Sydney, 2006, Sydney, NSW, Australia;TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, 300457, Tianjin, P.R. China;Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, 300457, Tianjin, P. R. China;

关键词: Experimental evolution;    Chemostats;    Escherichia coli;    Duplication;    Heterozygous duplication;    Insertion sequence elements;    Frequency-dependent selection;    Indirect selection;   

DOI  :  10.1186/1471-2164-14-441

 received in 2012-10-22, accepted in 2013-03-08,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundDNA duplications constitute important precursors for genome variation. Here we analyzed an unequal duplication harboring a beneficial mutation that may provide alternative evolutionary outcomes.ResultsWe characterized this evolutionary event during experimental evolution for only 100 generations of an Escherichia coli strain under glucose limitation within chemostats. By combining Insertion Sequence based Restriction Length Polymorphism experiments, pulsed field gel electrophoresis and two independent genome re-sequencing experiments, we identified an evolved lineage carrying a 180 kb duplication of the 46’ region of the E. coli chromosome. This evolved duplication revealed a heterozygous state, with one copy harboring a 2668 bp deletion that included part of the ogrK gene and both the yegR and yegS genes. By genetically manipulating ancestral and evolved strains, we showed that the single yegS inactivation was sufficient to confer a frequency dependent fitness increase under the chemostat selective conditions in both the ancestor and evolved genetic contexts, implying that the duplication itself was not a direct fitness contributor. Nonetheless, the heterozygous duplicated state was relatively stable in the conditions prevailing during evolution in chemostats, in striking contrast to non selective conditions in which the duplication resolved at high frequency into either its ancestral or deleted copy.ConclusionsOur results suggest that the duplication state may constitute a second order selection process providing higher evolutionary potential. Moreover, its heterozygous nature may provide differential evolutionary opportunities in alternating environments. Our results also highlighted how careful analyses of whole genome data are needed to identify such complex rearrangements.

【 授权许可】

Unknown   
© Maharjan et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.